Bone implants and methods

ABSTRACT

The disclosure provides implants, instruments and methods for bone fusion procedures. In some embodiments, the implants are particularly advantageous for use between opposing vertebral bodies to facilitate stabilization or arthrodesis of an intervertebral joint. The implants include, at least, a support component that provides structural support during fusion. In a typical embodiment, the implants also include a growth component. A growth component provides an environment conducive to new bone growth between the bones being fused. Several unique configurations to enhance fusion, instruments for insertion and methods for insertion are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/080,375, filed Feb. 19, 2002, which claims the benefit of U.S.Provisional Application No. 60/269,777, filed Feb. 16, 2001, and is acontinuation-in-part of U.S. application Ser. No. 09/896,926, filed Jun.28, 2001, now U.S. Pat. No. 6,635,060, which is a continuation-in-partof U.S. application Ser. No. 09/611,237, filed Jul. 6, 2000, now U.S.Pat. No. 6,641,582, which applications are incorporated herein byreference.

FIELD OF THE INVENTION

This invention pertains to bone implants, instruments and procedures.Specifically, the invention provides bone implants, instruments andmethods to facilitate fusion of bone. The invention is particularlysuited for stabilization or fusion of the intervertebral disc spacebetween adjacent vertebrae.

BACKGROUND OF THE INVENTION

Chronic back problems cause pain and disability for a large segment ofthe population. Frequently, the cause of back pain is traceable todiseased disc material between opposing vertebrae. When the discmaterial is diseased, the opposing vertebrae may be inadequatelysupported, resulting in persistent pain. Surgical techniques have beendeveloped to remove all or part of the diseased disc material and fusethe joint between opposing vertebral bodies. Stabilization and/orarthrodesis of the intervertebral joint can reduce the pain associatedwith movement of a diseased intervertebral joint. Spinal fusion may beindicated to provide stabilization of the spinal column for a widevariety of spine disorders including, for example, structural deformity,traumatic instability, degenerative instability, post-resectioniatrogenic instability, etc.

Generally, fusion techniques involve partial or complete removal of thediseased disc and packing the void area with a suitable matrix forfacilitating a bony union between the opposing vertebral bodies.

Surgical devices for facilitating interbody fusion are known. Somedevices are positioned external to the intervertebral joint during thefusion process. Other devices are positioned within the intervertebraljoint. Devices positioned within the joint space typically distract thejoint space and provide stabilization by causing tension on the annulusfibrosus and other supporting tissues surrounding the joint space.Examples of devices positioned within the joint space are disclosed in,for example, U.S. Pat. Nos. 5,458,638, 5,489,307, 5,055,104, 5,026,373,5,015,247, 4,961,740, 4,743,256 and 4,501,269, the entire disclosures ofwhich are incorporated herein by reference. Some systems use bothexternal fixation and internal fixation devices.

Regardless of the type or location of the fusion device, a bone graftand/or other implant is often used to facilitate new bone growth. Thesurface area, configuration, orientation, surface texture and deformitycharacteristics of an implant or bone graft placed in the disc space canaffect the stability of the joint during fusion and thus affect theoverall success of a fusion procedure.

Accordingly, the present invention is directed to unique implants orbone grafts that can be inserted at a fusion site, with or without otherstabilizing systems, and instruments and methods for inserting the same.

SUMMARY OF THE INVENTION

One inventive aspect of the present disclosure relates to an implant(e.g., a spinal implant) having a first component having supportmechanical characteristics and a second component having mechanicalcharacteristics for allowing bone in-growth. Other inventive aspectsinclude systems and methods for implanting multi-component implants. Itshould be noted that the examples are provided for illustrative purposesand are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an implant that is an embodiment of theinvention;

FIG. 2 is a top plan view of the implant of FIG. 1;

FIG. 3 is a front elevational view of the implant of FIG. 1;

FIG. 4 is a side elevational view of the implant of FIG. 1;

FIG. 5 is a perspective view of a portion of the implant of FIG. 1;

FIG. 6 is a front elevational view of the implant of FIG. 5;

FIG. 7A is a perspective view of an implant cap that is an embodiment ofthe present invention;

FIG. 7B is a side elevational view of the cap of FIG. 7A;

FIG. 7C is a top plan view of the cap of FIG. 7A;

FIG. 7D is a front elevational view of the cap of FIG. 7A;

FIG. 8A is a top plan view of an inferior vertebrae prior to apreparation step according to the principles of the present invention;

FIG. 8B is a front elevational view of the inferior vertebrae of FIG. 8Aand a corresponding superior vertebrae;

FIG. 9A is a top plan view of the inferior vertebrae of FIG. 8A after apreparation step according to the principles of the present invention;

FIG. 9B is a front elevational view of the inferior vertebrae and thesuperior vertebrae of FIG. 8B after the preparation step of FIG. 9A;

FIG. 10A is a top plan view of the inferior vertebrae of FIG. 9A afteranother preparation step according to the principles of the presentinvention;

FIG. 10B is a front elevational view of the inferior vertebrae and thesuperior vertebrae of FIG. 9B after the preparation step of FIG. 10A;

FIG. 11 is a front elevational view of the inferior vertebrae and thesuperior vertebrae of FIG. 10B after placement of a support member inaccordance with the present invention;

FIG. 12 is a front elevation view of the inferior vertebrae and thesuperior vertebrae of FIG. 11 after placement of a growth member inaccordance with the present invention;

FIG. 13 is a perspective view of an implant kit that is an embodiment ofthe present invention;

FIG. 14 is a perspective view of a wedge and portal assembly of theimplant kit of FIG. 13;

FIG. 15 is a top plan view of a rasp that is an embodiment of thepresent invention;

FIG. 16 is a side elevational view of the rasp of FIG. 15;

FIG. 17 is a proximal end-on elevational view of the rasp of FIG. 15;

FIG. 18 is an enlarged partial perspective view of teeth on a rasp headof FIG. 15;

FIG. 19 is an enlarged partial top plan view of a rasp head of the raspof FIG. 15;

FIG. 20 is a top plan view of a bone-cutting instrument that is anembodiment of the present invention;

FIG. 21 is a side elevational view of the bone-cutting instrument ofFIG. 20;

FIG. 22 is a distal end-on elevational view of the bone-cuttinginstrument of FIG. 20;

FIG. 23 is a top plan view of an implant insertion tool that is anembodiment of the present invention;

FIG. 24 is a side elevational view of the implant insertion tool of FIG.23;

FIG. 25 is a distal end-on elevational view of the implant insertiontool of FIG. 23;

FIG. 26 is a side elevational view of a sleeve that is an embodiment ofthe present invention;

FIG. 27 is a cross-sectional view of the sleeve of FIG. 26;

FIG. 28 is an end-on elevational view of the sleeve of FIG. 26;

FIG. 29 is a top plan view of an insertion tool handle that is anembodiment of the present invention;

FIG. 30 is a cross-sectional view of the handle of FIG. 29 taken alongline 30-30

FIG. 31 is an end-on elevational view of the handle of FIG. 29;

FIG. 32 is side elevational view of an implant insertion tool that isanother embodiment of the present invention;

FIG. 33 is a top plan view of the implant insertion tool of FIG. 32;

FIG. 34 is a perspective view of a portal insertion step according tothe principles of the present invention;

FIG. 35 shows a vertebrae preparation step using a rasp according to theprinciples of the present invention;

FIG. 36 shows a vertebrae preparation step using a box chisel accordingto the principles of the present invention;

FIG. 37 is a perspective view of a support member being positioned uponan incertion tool according to the principles of the present invention;

FIG. 38 shows a support member insertion step according to theprinciples of the present invention;

FIG. 39 is shows a growth member insertion step according to theprinciples of the present invention;

FIG. 40 shows a portal extraction step according to the principles ofthe present invention;

FIG. 41 is a perspective view of an implant that is another embodimentof present invention;

FIG. 42 is a side elevational view of the implant of FIG. 41;

FIG. 43 is a front elevational view of the implant of FIG. 41; and

FIG. 44 is a top plan view of the implant of FIG. 41.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed toward the fusion of bones. Theinvention provides natural and/or synthetic bone implants that canfunction as a bone graft between adjacent bones to be fused. Theimplants of the invention include unique arrangements, configurationsand components to facilitate fusion and maintain stability during thefusion process.

The implants, instruments and methods of the invention can be used in avariety of bone fusion procedures. In some embodiments, the inventionmay be particularly advantageous for intervertebral stabilization orarthrodesis of the intervertebral disc space between adjacent vertebrae.Accordingly, for purposes of description herein, the invention will bedescribed by reference to intervertebral fusion procedures in the lumbarregion of the spine. However, this description is for exemplary purposesonly and should not be construed to limit the intended scope of use ofthe disclosed implants, instruments or methods. For example, in the caseof vertebral fusion, the implants, instruments and methods of theinvention can be used to fuse cervical, thoracic, lumbar or lumbo-sacralvertebrae.

In general, the implants, instruments and methods of the invention aredirected to facilitating greater continuity between the bone formed atthe fusion site and the bones fused. The implants are also designed toprovide greater structural support at the fusion site to maintainstability and alignment at the fusion site, to reduce healing time andoptimize the structural integrity of the new bone formed at the fusionsite. The implants of the invention can also facilitate the ease ofimplanting and positioning implants at a fusion site.

The implants can be prepared from natural materials, syntheticmaterials, or a combination of natural and synthetic materials. As usedherein, “natural material” means “bone” and includes bone harvested fromhumans or animals. “Bone” may further include heterologous, homologousand autologous (i.e., xenograft, allograft, autograft) bone derivedfrom, for example, fibula, tibia, radius, ulna, humerus, cranium,calcaneus, tarsus, carpus, vertebra, patella, ilium, etc. Bone mayfurther include one or more bone products which have been partially orcompletely demineralized, prepared for transplantation (e.g., viaremoval of immunogenic proteins), and/or processed by other techniques.Additionally, the implants can be prepared from products made from bone,such as chips, putties, and other similar bone products. In someembodiments, human source bone is preferred for human applications. In apreferred embodiment, the bone of an implant can be cancellous and/orcortical.

Cortical implant material can be obtained from known long bones, such asthe humerus, radius, ulna, tibia, femur, fibula, etc. Cancellousmaterial can be obtained from the patella, distal condyles, tibialplateau, femoral head, etc. Cranial, pelvic (e.g. iliac crest) andpatellar bone can advantageously provide both cortical and cancellousbone in a single piece. Indeed, these sources can provide an implanthaving cancellous bone surrounded on opposing sides by cortical bone.

“Synthetic materials” include non-bone materials such as titanium,stainless steel, porous titanium, ceramic, carbon fiber, silicon,methylmethacrylate, polytetrafluoroethylene, polycarbonate urethane,PEEK and other materials suitable for use as an orthopedic implant.Further, the materials may include any of the above synthetic materialscombined with a natural bone material. For example, the material maycomprise a combination of bioglass and bone chips or bone chips with abonding agent. As stated above, an implant of the invention can consistsolely of a synthetic material. In other applications, a syntheticmaterial may be used in combination with cancellous bone.

In one embodiment, an implant can include a support component or memberand a growth component or member. The support component includes amaterial having mechanical properties suitable for providing, support,stabilization or alignment at the fusion site. An exemplary material forthe support component includes cortical bone. The growth componentincludes a material having mechanical or physical properties that allowor support new bone in-growth. An exemplary material for the growthcomponent includes cancellous bone. In such an embodiment, the supportcomponent of the implant provides strength for column support and/orstabilization, and the growth component facilitates tissue growth,vascularization and deposition of new bone (e.g., by providing increasedsurface area). In one embodiment, the support component includes amaterial that provides greater axial column strength than the growthcomponent, and the growth component includes a material that allows forenhanced bone in-growth as compared to the support component.

As indicated above, in some embodiments, the “support” portion(component) of an implant of the invention is provided by cortical boneor a natural or synthetic material having biomechanical and biologicalcharacteristics similar to cortical bone. The support portion providessupport, stabilization, and facilitates alignment at the fusion site.The “growth” portion (component) of the implant can include a materialthat allows bone in-growth (i.e., an osteoconductive material) such as abone growth matrix. In these embodiments, the growth portion provides amatrix or scaffold to support new bone growth. One preferred bone growthcomponent that can also provide some support is cancellous bone.“Porous” synthetic materials can also act as a supporting, growthcomponent. As used herein, a “porous synthetic material” includes, forexample, porous titanium, porous ceramics, porous stainless steel andlike materials. Such porous materials can provide characteristics ofboth the growth portion and the support portion of the implant.

In some embodiments, the growth component of the implant can be preparedfrom cancellous bone or alternatively a bone growth matrix shaped intoany one of the advantageous configurations of growth componentsdisclosed herein. Suitable bone growth matrices can be resorbable ornonresorbable, and with or without osteoinductive properties ormaterials. Examples of suitable osteoconductive matrices includesynthetic materials, such as Healos™, available from Orquest, MountainView, Calif. Examples of osteoinductive materials include bone marrow,blood platelets and/or bone morphogenic proteins (BMPs).

An implant of the invention can have one of several configurationsincluding a single component or a plurality of components. In oneembodiment, the implants have first and second bearing surfaces, whichin use are positioned adjacent opposing vertebrae endplates. The bearingsurfaces can include an engaging surface having a surface texture thatenhances stability at the bone-implant interface and reduces thelikelihood of motion during the fusion process. Examples of engagingsurfaces suitable for the invention include ridges, knurls, grooves,teeth, serrations, etc.

Natural or synthetic bone implants of the invention can be manufacturedusing procedures known in the art. Methods for preparing natural boneimplants are disclosed in for example, U.S. Pat. Nos. 6,033,438;5,968,047; 5,585,116; 5,112,354; and 5,439,684; the entire disclosuresof which are incorporated herein by reference.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The implants, instruments and methods of the invention will now bedescribed by reference to the several drawing figures. The functionalfeatures of the implants of the invention can be embodied in any of anumber of specific configurations. It will be appreciated, however, thatthe illustrated embodiments are provided for descriptive purposes andshould not be used to limit the invention. In addition, in manyexemplary embodiments, cortical and cancellous bone are used. It will beappreciated from an understanding of the present invention that thecortical or support and/or growth portions of the implants can besubstituted with synthetic materials.

I. Representative Bone Implant

FIGS. 1-4 illustrate a multi-piece bone implant 320 that is arepresentative embodiment of the present invention. The bone implant 320includes a bone support member 341 (also referred to as a supportcomponent or support portion) configured for intervertebralimplantation. As best shown in FIG. 1, the bone support member 341defines a cavity 327 (i.e., a void, pocket or channel) having an openend 342 positioned opposite from a closed end 343. The bone implant 320also includes a growth member 321 (also referred to as a growthcomponent or growth portion) having a shape that generally correspondsto or matches (i.e., complements) a shape of the cavity 327. The openended configuration of the cavity 327 allows the growth member 321 to beinserted into the cavity 327 through the open end 342. In oneembodiment, the growth member 321 is inserted after the bone supportmember 341 has been implanted between adjacent vertebrae. In anotherembodiment, the bone support member 341 is implanted such that the openend 342 of the bone support member 341 faces in an anterior direction(i.e., toward the ventral surface of the patient), and the growth member321 is inserted into the cavity 327 using an anterior approach.Alternatively, the open end 342 may face in an anterior-lateral orlateral direction and the growth member 342 may be inserted using ananterior-lateral or lateral approach, respectively.

A. Bone Support Member

Referring to FIG. 2, the bone support member 341 of the implant 320 hasa generally “C-shaped” configuration and includes outer and inner wallsurfaces 323, 324. The shape of the bone support member 341 can also bedescribed as “partial ring-shaped”, “U-shaped”, “semi-annular”, orgenerally “horseshoe-shaped”. In a preferred embodiment, the bonesupport member 341 includes first and second arms 325, 326 that areintegrally connected at mid-line ML. Interior portions of the arms 325,326 oppose one another so as to define the cavity 327 of the supportmember 341 therebetween. For example, the inner wall surface 324includes opposing portions 325 a and 326 a, respectively, defined by thearms 325, 326. The opposing portions 325 a, 326 a extend on oppositesides of the mid-line ML from the open end 342 of the cavity 327 to theclosed end 343 of the cavity 327.

Referring still to FIG. 2, the opposing portions 325 a, 326 a of theinner wall surface 324 include opposing curved portions 325 b, 326 blocated adjacent the closed end 342 of the cavity 327 and opposingplanar portions 325 c, 326 c located adjacent the open end 342 of thecavity 327. The curved portions 325 b, 326 b are shown having a concave,circular curvature. The planar portions 325 c, 326 c are generallyparallel and define an insertion channel 371 for guiding the growthmember 321 into the cavity 327 during insertion, and for aligning thegrowth member 321 within the cavity 327. In a preferred embodiment, theinsertion channel is sufficiently wide between the planar portions 325c, 326 c to receive the growth member 321 therein without requiring thearms 325, 326 to be flexed apart. The outer wall surface 323 of thesupport member 341 is shown including a convex, circular curvature thatis concentric with the curvature defined by the curved portions 325 b,326 b of the inner wall surface 324. In other embodiments, the supportmember 341 may be non-circular and/or not curved at all. For example,the support member 341 could include other shapes such as rectangles,squares, ovals, ellipses, etc.

FIGS. 5 and 6 illustrate the support member 341 with the growthcomponent 321 removed from the cavity 327. As can be seen, inner wall324 includes a first groove 336 extending partially along first arm 325and a second groove 337 extending partially along second arm 326. Thegrooves 336, 337 (e.g., slots) oppose one another and extend from theopen end 342 of the cavity 327 toward the closed end 343 of the cavity327. At least portions of the grooves 336, 337 are preferably defined bythe planar portions 325 c, 326 c of the inner wall surface 324. Althoughgrooves 336 and 337 are shown as being discontinuous, the groove can becontinuous around inner wall 324. As will be described below, grooves336 and 337 provide for attachment of a cover 350 (FIGS. 7A-7D) or animplant insertion tool 800 (FIGS. 23 and 24). While the grooves 336, 337are shown including rectangular cross-sections, other shapedcross-sections such as rounded or triangular shapes could also be used.Further, the portions of the tool 800 or the cover 350 may or may not becomplementary with the shapes of the grooves.

Referring to FIG. 4, the bone support member 341 includes first andsecond bearing surfaces 328, 329 separated by a height or thickness ofthe support member 341. The inner and outer wall surfaces 323, 324extend generally perpendicularly between the first and second bearingsurfaces 328, 329. In the illustrated embodiment, the first bearingsurface 328 includes an engaging surface comprising ridges 328 a, andthe second bearing surface 329 includes an engaging surface comprisingridges 329 a. As discussed previously, engaging surfaces reduce thelikelihood of post-implantation mobility of an implant.

Referring to FIGS. 5 and 6, the cavity 327 of the bone support member341 preferably extends completely through the bone support member 341between the top load bearing surface 328 and the bottom load bearingsurface 329. Thus, the cavity 327 is open on the top and bottom sides ofthe bone support member 341 to facilitate exposure of top and bottomsurfaces of the growth member 321 to the endplates of adjacent vertebraewhen the growth member 321 positioned within the cavity 327.

While the bone support member 341 can have a constant height, in apreferred embodiment, the support member 12 is slightly tapered so as todefine a wedge shape. In one embodiment, the bone support member 341 caninclude a lordotic taper at an angle θ in the range of 0-16 degrees (seeFIG. 4). As shown in FIG. 4, in an exemplary embodiment with a lordotictaper, the support member 341 has a maximum thickness H_(max) adjacentthe open end 342 of the cavity 327 and a minimum thickness H_(min)adjacent the closed end 343 of the cavity 327. In certain embodiments, agradual taper is provided between the two thicknesses H_(max) andH_(min).

In one non-limiting embodiment, the support member 341 can have amaximum depth D in the range of 20-30 mm, a maximum width W in the rangeof 20-30 mm, an average thickness (the average of the two thicknessesH_(max) and H_(min)) in the range of 6-24 mm. In another embodiment, thesupport member 341 is made of a homogeneous material having consistent(i.e., non-varying) mechanical properties. For example, in oneembodiment, the support member 341 can include a bone material having aconsistent degree of mineralization. In other embodiments, the supportmember 341 can include regions of decreased mineralization (e.g.,demineralized portions) that provide regions of increased flexibility.In a preferred embodiment, the support member 341 includes a corticalbone cross-section from a femur or tibia bone.

B. Bone Growth Member

In certain embodiments, the growth member 321 preferably has apre-manufactured or pre-formed shape. The terms “pre-manufactured” and“pre-formed” mean that the growth member 321 has a pre-defined shapeprior to insertion in the cavity 327. In some embodiments, thepre-manufactured shape of the growth member 321 complements the shape ofthe cavity 327. In certain other embodiments, the growth member 321includes multiple sub-units having pre-defined individual shapes and/orhaving collective shapes. In another embodiment, the growth member 321includes a block of cancellous bone having a shape that complements theshape of the cavity 327.

As shown in FIG. 2, the bone growth member 321 includes a first end 370positioned opposite from a second end 372. The first end 370 includes anend curvature that generally matches the curvature of the inner wallsurface 324 adjacent the closed end 343 of the cavity 327. The bonegrowth member 321 also includes substantially parallel sidewall surfaces374 that extend between the first and second ends 370 and 372. Thesecond end 372 of the bone growth member 321 includes a substantiallyplanar surface 376 that extends between the sidewall surfaces 374. Inone preferred embodiment, the planar surface 376 is generallyperpendicular relative to the sidewall surfaces 374. The bone growthmember 321 also may include top and bottom surfaces 378 and 380 that aregenerally parallel relative to one another. In the embodiment shown, thetop and bottom surfaces 378 and 380 extend between the first and secondends 370 and 372 of the bone growth member 321 and are generallyperpendicular relative to the sidewall surfaces 374 and the planar endsurface 376. In the depicted embodiment, the bone growth member 321 hasa thickness H_(gm) that is substantially constant from the first end 370to the second end 372. In alternative embodiments, the thickness cantaper gradually along the entire or part of the distance between thefirst and second ends 370 and 372. In some preferred embodiments, thethickness H_(gm) of the bone growth member 321 is greater than thethickness H_(max) of the bone support member 341. In these embodiments,the thickness H_(gm) is preferably at least 2 or 3 mm greater than thethickness H_(max).

In certain embodiments, the top and bottom surfaces 378 and 380 areadapted for direct contact with cancellous bone upon implantation. Inthese embodiments, to promote bone growth, it is desirable for thesurface area provided by the top and bottom surfaces 378 and 380 toprovide a significant portion of the total contact area provided by theimplant 320 (the combined contact area provided by both the supportmember 341 and the bone growth member 321). In one embodiment, the topand bottom surfaces 378 and 380 provide at least 20 percent of the totalcontact area. In another embodiment, the top and bottom surfaces 378 and380 provide at least 25 percent of the total contact area. In stillanother embodiment, the top and bottom surfaces 378 and 380 provide atleast 30 or 40 percent of the total contact area. In a furtherembodiment, the top and bottom surfaces 378, 380 each have a widthW_(gm) (shown in FIG. 2) at least 40 percent as wide as the width W ofthe support member 341, and a depth D_(gm) (shown in FIG. 2) at least 50percent as deep as the depth D of the support member 341.

In a preferred embodiment, the bone growth member 321 has a non-threadedexterior. In this embodiment, the bone growth member 321 can be insertedinto the cavity 327 by sliding the growth member 321 therein withoutrequiring rotation. Additionally, the non-threaded configuration of thegrowth member 321 eliminates the need for tapping threads into the bonesupport member 341 or the opposing vertebral end plates between whichthe growth member 321 is desired to be implanted.

Referring to FIG. 3, the bone implant 320 has a dome shape for limitingend plate removal and thereby minimizing subsidence. By “dome shape”, itis meant that the implant is curved or tapered on the top and bottomsurfaces 378 and 380 such that a thickness of the implant increases in adirection extending from the outer perimeter of the support member 341toward the mid-line ML. In one embodiment, the degree of curvature ofthe dome is defined by a 3-inch radius.

Other implant configurations are disclosed in U.S. application Ser. Nos.60/325,585 and 60/325,804 which are hereby incorporated by reference.

C. End Cap

FIGS. 7A-7D illustrate an optional cap 350 for positioning in cavity 327between arms 325 and 326. In the illustrated embodiment, cap 350 has afirst bearing surface 351, a second bearing surface 352, an innersurface 353 and an outer surface 354. Bearing surface 351 includes anengaging surface 352 which can be similar to that of implant 320(bearing surface 352 can also include an engaging surface). On eachside, cap 350 includes a tab 360 and 361. Tabs 360 and 361 areconfigured to pass into grooves 337 and 336. As illustrated in FIGS. 7Aand 7B, tab 360 (and 361) have a major height G_(M), and minor heightG_(m). The difference in height G_(M) and G_(m) provides tabs 360 and361 with a diverging taper from inner surface 353 to outer surface 354.Thus, when tabs 360 and 361 have passed into grooves 337 and 336 as cap350 is advanced within arms 325, 326 the taper from height G_(m) toheight G_(m) is selected to provide for a snug fit between tabs 360 and361 and grooves 336 and 337 to retain cap 350 in position. That is, cap350 is friction fit into implant 320. The grooves 336 and 337 of implant320, and a cap, such as cap 350 can be used with other implants, such asimplants 120 and 140.

Cap 350 can also include a bore 365 that may be threaded (not shown)which permits for attachment of an insertion tool having a threaded maleend to mate with bore 365.

II. General Implantation Method

To implant the implant 320, a discectomy is performed on a patient topartially or completely remove a diseased disc between adjacentvertebrae 20, 22 (see FIGS. 8A and 8B). With the disc material removed,end plates 20′, 22′ of the adjacent vertebra 20, 22 aredistracted/separated (e.g., with a wedge distractor). After the vertebra20, 22 have been spaced-apart, first regions 24 (see FIGS. 9A and 9B) ofthe end plates 20′, 22′ are prepared/conditioned to receive the boneimplant 10. For example, the end plates 20′, 22′ can be conditioned byrasping the end plates 20′, 22′ to remove cartilaginous material fromthe end plates 20′, 22′ and to smooth the cortical bone of the endplates 20′, 22′ by reducing surface irregularities. Next, second regions26 of the end plates 20′, 22′ are prepared within the first regions 24(see FIGS. 10A and 10B). In a preferred embodiment, the second regions26 have smaller areas than the first regions 24 and are subsets or subregions of the first regions 24. In one embodiment, the second regions26 are prepared by using a cutting tool (e.g., a chisel) to remove thecortical bone from the second regions 26 and expose underlyingcancellous bone. In this embodiment, the exposed cancellous bone at thesecond regions 26 is preferably surrounded by partial rings 27 ofcortical bone (e.g., including the epiphyseal ring).

After preparation of the end plates 20′, 22′, the bone support member341 is inserted between the distracted vertebrae 20, 22 (see FIG. 11).As so inserted, the top and bottom load bearing surfaces 328, 329 of thesupport member 341 directly engage the partial rings 27 of cortical boneto provide column support. After implantation of the support member 341,the bone growth member 321 is inserted into the cavity 327 through theopen end 342. As so inserted, the top and bottom sides 378 and 380 ofthe growth member 341 directly contact the exposed cancellous bone ofthe second regions 26 to provide a fusion lattice (see FIG. 12).

In a preferred embodiment, each first region 24 is co-extensive with amajority of the surface area of each end plate 20′, 22′. As shown inFIGS. 9A and 9B, each first region 24 covers substantially all of thesurface area of each corresponding end plate 20′, 22′. Thus, in such anembodiment, the implant 320 is sized to fill a majority of theintervertebral space between the end plates 20′, 22′ and to contact amajority of the surface area of each end plate 20′, 22′. In oneembodiment, each second region 26 defines an area that coincides with20-80 percent of the total area defined by each corresponding firstregion 24. In another embodiment, each second region 26 defines an areathat coincides with 30-70 percent of the total area defined by eachcorresponding first region 24. In yet another embodiment, each secondregion 26 defines an area that coincide, with 40-60 percent of the totalarea defined by each corresponding first region 24.

III. Implantation Kit

FIG. 13 illustrates an embodiment of a kit (i.e., an instrument set) forimplanting the bone implant 320 of FIG. 1. The kit includes a wedgedistractor 50 for providing a desired spacing between two vertebraedesired to be stabilized. The kit also includes a portal 52 formaintaining the spacing between the vertebrae after the wedge distractor50 has been removed from between the vertebrae. The portal 52 includes awindow 54 for allowing access to the space between the distractedvertebrae. Certain embodiments of the wedge distractor and portal systemhave previously been disclosed in U.S. Pat. No. 6,224,599, incorporatedherein by reference. The kit further includes instruments that can beinserted through the window 54 of the portal 52 for preparing thevertebral end plates. For example, the kit includes a rasp 600 forremoving cartilage from the vertebral end plates and for conditioningthe cortical bone of the vertebral end plates. A box chisel 510 isincluded in the kit for removing cortical bone from the vertebral endplates to provide regions of exposed cancellous bone.

The box chisel 510 includes a hollow handle 518 configured to slide overa shaft 603 of the rasp 600 such that the shaft 603 functions as a guidefor controlling the cutting location of the chisel 510. A side handle701 having an alignment pin 703 is adapted to maintain rotationalalignment between the rasp 600 and the box chisel 510. The alignment pin703 inserts within an opening 605 defined by the shaft 603 of the rasp600 and also extends through a slot 550 defined by the handle 518 of thechisel 510. The slot 550 allows the chisel 510 to be moved axially backand forth along the rasp handle to provide a chiseling motion. As thechisel 510 is moved along the rasp handle, the pin 703 slides along theslot 550. The range of axial motion of the chisel 510 is limited by thelength of the slot 550. During chiseling, the side handle 701 ispreferably grasped to stabilize the rasp 600. A slap hammer 501 can beused to provide greater impact forces for cutting the vertebrae with thechisel 510. The slap hammer 501 includes a slot 503 for allowing theslap hammer 501 to be moved past the alignment pin 703 when slid overthe handle 518 of the chisel 510.

The kit further includes an insertion tool 800 having an insertion head803 (also referred to as a “working end”) sized to fit within the cavity327 of the bone support member 341. In use, the bone support member 341is mounted on the insertion head 803, and the insertion tool 800 is usedto insert the bone support member 341 between the distracted andpre-conditioned vertebrae. Thereafter, the insertion head 803 is removedfrom the cavity 327 of the bone support member 341, and the growthmember 321 is inserted into the cavity 327 through the open end 342 ofthe cavity 327. Alternatively, a conventional tool, such as a forceps,can be used to insert the growth member 321 into the cavity 327. Afterthe implant 320 has been implanted into the intervertebral space, aportal extractor 60 can be used to remove the portal 52.

A. Wedge Distractor, Portal and Portal Extractor

FIG. 14 shows the wedge distractor 50 and the portal 52 of the kit ofFIG. 13 in alignment with one another. The wedge distractor 50 includesa generally rectangular base portion 64. A back side 65 of the baseportion 64 defines a threaded opening (not shown) sized to receive athreaded end of a handle 66. A vertebral wedge 68 projects forwardlyfrom a front side 67 of the base portion 64.

The portal 52 includes a generally rectangular frame 70 defining theportal window 54. The portal window 54 is sized to receive the wedgedistractor 50 with a friction fit between the base portion 64 of thewedge distractor 50 and the frame 70 of the portal 52. The portal 52also includes spaced apart distraction paddles 74 that align on oppositesides of the vertebral wedge 68 when the wedge distractor 50 is pressfit within the portal 52. The distraction paddles 74 and the vertebralwedge 68 preferably have substantially the same side profile.

Referring to FIG. 13, the portal extractor 60 is sized to fit withinwindow 54 of portal 52. Handle 66 (shown in FIG. 14) preferably connectsto extractor 60. Tab 63 of extractor 60 fits within opening 65 of portal52 to allow portal 52 to be pulled from the intervertebral space.

B. Rasp

FIG. 15 is a top view and FIG. 16 a side view of the rasp 600 of the kitof FIG. 13. The rasp 600 is adapted to function as both as a trialsizer, i.e. for a particularly sized and shaped implant, and a rasp.Rasp 600 has a proximal end 601 and a distal end 602 spaced alonglongitudinal axis X-X. At the proximal end 601 of shaft 603, there is aroughened area 604 that can be in the form of knurls, etchings, grooves,ridges, or other suitable patterns to enhance manual gripping of theshaft 603. The opening 605 for receiving the alignment pin 703 of handle701 extends transversely through the proximal end 601 of the shaft 603.As previously indicated, the opening 605 and alignment pin 703 assist inmaintaining rotational alignment between the rasp 600 and the chisel510.

At the distal end 602, rasp 600 includes a rasp head 606. In theillustrated embodiment, rasp head 606 includes an outer wall 607, aninner wall 608 and has a generally “C-shaped” configuration with a firstarm 609 continuous with a second arm 610. The inner wall 608 defines apocket or receptacle which is sized to complement and receive the distalend of the chisel 510. The first arm 609 and second arm 610 are spacedapart from the shaft 603. Rasp head 606 includes a first engagingsurface 611 and a second engaging surface 612. In the illustratedembodiment, the first and second engaging surfaces 611, 612 have ridges613 (see FIGS. 17-19). In alternative embodiments, knurls, etchings,teeth, grooves or other suitable patterns may be substituted for ridges613.

As illustrated best in FIG. 17, in this embodiment, rasp head 606 has amajor height H_(M) and minor height H_(m). The taper from the majorheight to the minor height can be from about 0° to about 16°. The shapeand configuration of the rasp head 606 corresponds to the shape andconfiguration of an implant. In one embodiment, the rasp head 606corresponds in size and configuration with the support component 341 ofthe two-part implant 320 of FIGS. 1-4. In such an embodiment, the rasphead 606 preferably has the same lordotic taper angle and the same domecurvature as the support member desired to be implanted. The spacebetween the first and second arms 609, 610 of the rasp head 606corresponds generally with the shape of the growth component 321 of theimplant 320. It will be appreciated, however, that the configuration ofthe rasp head 606 can be square, rectangular, circular, oval, etc.,depending on the configuration of the implant(s) to be inserted into thechannel.

As a trial sizer, the rasp 600 provides a means for determining theappropriate size bone cutting instrument and implant to use for aparticular implant site. Multiple rasps 600 are provided, withincrementally different sized, shaped, and/or tapered rasp heads 606corresponding to different sized, shaped, and/or tapered implants. Thesurgeon inserts and removes the various rasps 600 and determines (e.g.,via evaluation of the frictional fit) which one is the correct size forthe intervertebral space. The ridges 613 on the upper and lower surfacesof the rasp head act as a rasp to condition the end plates of the upperand lower adjacent vertebrae.

Proximal to the distal end 602, the shaft 603 of the rasp 600 alsoincludes markings 614 at predetermined distances from the distal edge615 of the rasp head. During use, markings 614 provide the surgeon withan indication of the depth of distal penetration of rasp 600 betweenadjacent vertebrae.

C. Box Chisel

FIG. 20 is a top view and FIG. 21 a side view of the chisel 510 shown inthe kit of FIG. 13. Chisel 510 has a proximal end 515 and a distal end516 spaced along longitudinal axis X-X. At the proximal end 515 of shaft517 there is a handle 518 for operating chisel 510. The handle 518 has aroughened area 519 that can be in the form of knurls, etchings, grooves,ridges, or other suitable patterns to enhance manual gripping of thehandle 518. At the distal end 516, chisel 510 includes a first cuttingedge 520, a second cutting edge 521, and third and fourth cutting edges522 and 523. In the illustrated embodiment, cutting edges 520, 521, 522and 523 are at the distal end of chamber 525. First, second, third, andfourth cutting edges 520, 521, 522 and 523 are beveled 520 a, 521 a, 522a, and 523 a, respectively, to facilitate cutting and removal of bone.An internal hollow bore 527 extends from the proximal end 515 throughthe chisel 510 to the distal end 516 to receive the shaft 603 of rasp600 and to receive bone.

In the illustrated embodiment, elongated openings 550 and 551 extendthrough the handle 518 and shaft 517, respectively, of the chisel 510.As described previously, opening 550 allows for alignment of the chisel510 with rasp 600. Opening 551 provides additional access to theinternal bore 527 for cleaning the instrument and reduces the weight ofthe instrument.

FIG. 22 is a distal end-on view of chisel 510 showing that first andsecond cutting edges 520 and 521 define a height dimension C_(H) and thecutting edges 522 and 523 define a width dimension W_(C). The perimeterconfiguration of cutting edges 520, 521, 522, and 523 in FIG. 22 is arectangular shape particularly suited for preparing a channel or implantbore between adjacent bones for insertion of a two-part implant having aconfiguration such as that of the implant 320 shown in FIG. 1.

As previously indicated, implant 320 includes growth member 321, such ascancellous bone, and support member 341, such as cortical bone. Thegrowth member 321 has a similar size and shape as the distal end of thechisel 510 (e.g., dimension W_(gm) of growth member 321 corresponds todimension W_(C) of chisel 510 and dimension H_(gm) of growth member 321corresponds to dimension C_(H) of chisel 510). Also, the end curvature(i.e., at end 370) of the growth member 321 corresponds to the curvatureof edges 520 and 521 of the chisel 510. The support member 341 has asimilar size and configuration as the rasp head (see for example FIGS.15, 16). The support member 341 of the implant may be the same size asthe rasp head, or it can be larger or smaller than the rasp head. Thesupport member 341 of the implant can be about 0 mm to about 4 mm largerin height than the rasp head. The height dimension C_(H) of the chisel510 can be about 3 mm taller than the maximum height of the supportmember 321 of the implant. It will be appreciated, however, that theperimeter configuration of cutting edges 520, 521, 522, and 523 can besquare, circular, oval, etc., depending on the external configuration ofthe implant to be inserted into the channel. The length of the first andsecond cutting edges 520 and 521 can vary to correspond with the depthof the vertebrae.

To cut different sized channels, a set of chisels 510 will be availablewhich has instruments with incrementally different sizes of cuttingedges 520, 521, 522, 523 corresponding to a particular size implant. Forexample, chisels 510 having first and second cutting edges 520, 521 withdifferent heights C_(H) will be available to permit the surgeon toselect a cutting edge height corresponding to a particular disc spaceheight. In addition, it will be appreciated that the illustrated cuttingedges 520 and 521 (and 522 and 523) are parallel. In alternativeembodiments, cutting edges 520 and 521 (and 522 and 523) can form aconverging or diverging taper.

D. Insertion Tool

FIGS. 23-25 illustrate the insertion tool 800 of the kit of FIG. 13. Asillustrated, implant insertion tool 800 has a proximal end 801 and adistal end 802 having a working end 803. Working end 803 includes tabs804 and 805 that fit cooperatively within grooves 336, 337 of thesupport member 341 of the implant 320. In addition, the working end 803includes a slot 806 that permits resilient/elastic arms 807 and 808 toflex or expand laterally away from axis A_(T).

In a typical embodiment, arms 807 and 808 are spring biased to expandaway (e.g., laterally) from axis A_(T) in the normal, relaxed position.A sleeve 820 (FIGS. 26-28) can then be slid from the proximal end 801 ofthe insertion tool 800, over the slot 806, to force arms 807 and 808towards (e.g. medially) axis A_(T). That is, when the sleeve is advanceddistally it brings arms 807 and 808 together towards axis A_(T). In thisposition, the working end 803 of implant insertion tool 800 can beinserted into an implant. Similarly, where useful for additionalcontrol, tabs 804 and 805 can be inserted into grooves 336, 337 of animplant. The sleeve can then be slid towards the proximal end to allowarms 807 and 808 to expand away from axis A_(T) to provide frictionholding of an implant on the working end 803. After placement of animplant, the sleeve can be slid distally to bring arms 807 and 808 backtoward axis A_(T) to remove implant insertion tool 800, leaving theimplant in place. Other arrangements providing for expansion andcontraction of arms 807, 808, relative to axis A_(T) also arecontemplated by this disclosure

Thus, an implant can be mounted on the working end 803 of implantinsertion tool 800 allowing the surgeon to manipulate an implant viatool 800 into a suitable position at the fusion site.

Referring back to FIGS. 23 and 24, in one embodiment the insertion tool800 has a threaded region 809 at the proximal end 801. The threadedregion 809 threads within a distal end 851 of a handle 850 (shown inFIGS. 29-31). The handle 850 has a roughened area 852 that can be in theform of knurls, etchings, grooves, ridges, or other suitable patterns toenhance manual gripping of the handle 850. In one embodiment, the distalend 851 of the handle 850 has exterior threading to match internalthreading 821 on a sleeve 820. The sleeve 820 is hollow and has a bore822 extending from the proximal end 823 to the distal end 824, and whichis sized to fit over the proximal end 801 of the implant insertion tool800. When the sleeve 820 is not being used to force the arms 807, 808 ofthe insertion tool toward one another, the internal threadings 821 canbe threaded on the distal end 851 of the handle 850 to preventunintended sliding of the sleeve 820.

FIGS. 32 and 33 illustrate an alternative embodiment of an implantinsertion tool 400 suitable for use with an implant of the invention. Asillustrated, implant insertion tool 400 has a proximal end 401 includinga handle 402 for operating the instrument and a distal end 403 having aworking end 404. Working end 404 include tabs 405 and 406 that fitcooperatively within grooves 336 and 337 of implant 320. Thus, implant320 can be mounted at the working end 404 of implant insertion tool 400allowing the surgeon to manipulate implant 320 via tool 400 into asuitable position at the fusion site.

IV. Method of Implantation Using Kit

In one embodiment, a technique for practicing the method of FIGS. 8-12involves using the kit of FIG. 13. In practicing the method, a window,approximately the width of the portal 52 is cut, symmetrically about themidline, in the annulus and a complete discectomy is performed.Preferably, the lateral annulus is retained to act as a tension bandaround the implant 320.

After cutting the window in the annulus, the appropriate sized wedgedistractor 50 and portal 52 are selected based on pre-operativetemplating. A sizing chart for various components of the kit is setforth below. The dimensions listed correspond to the heights of portionsof the components that are inserted into the intervertebral space.INSTRUMENT LETTER CODE A B C D E PORTAL 10 mm 12 mm 14 mm 16 mm 18 mmDISTRACTOR WEDGE 10 mm 12 mm 14 mm 16 mm 18 mm RASP/TRIAL 10 mm 12 mm 14mm 16 mm 18 mm CORTICAL GRAFT 10 mm 12 mm 14 mm 16 mm 18 mm BOX CHISEL13 mm 15 mm 17 mm 19 mm 21 mm INSERTER HEAD 13 mm 15 mm 17 mm 19 mm 21mm CANCELLOUS BLOCK 13 mm 15 mm 17 mm 19 mm 21 mm

Once the wedge distractor 50 and portal 52 of the appropriate size havebeen selected, the portal 52 is inserted over the wedge distractor 50,and the combined unit is then delivered into the midline of the discspace until a desired spacing and annular tension is achieved betweenthe adjacent vertebrae 20, 22. Proper placement is achieved when theportal 52 is flush with the vertebrae 20, 22 as shown in FIG. 34. Theproper position of the portal 52 can be confirmed by utilizingfluoroscopy.

With the portal in the position shown in FIG. 34, the slap hammer 501can be used to help facilitate the removal of the wedge distractor 50from the portal 52. Additional discectomy or posterior decompression canbe completed, if necessary.

After the wedge distractor 50 has been removed, a rasp 600 of theappropriate size is selected. The end plates 20′, 22′ are then preparedby inserting the head of the rasp through the portal 52 and rasping inan anterior/posterior direction. Preferably, the rasp 600 is advanceduntil shoulder 607 of the rasp is adjacent the posterior most edge 51 ofthe portal 52 (see FIG. 35). In this position, the thickness of the rasphead is slightly larger (e.g., about one-half millimeter) than theportal paddles. In this manner, the rasp prepares the first regions 24of the end plates 20′, 22′ as shown in FIG. 9A. Fluoroscopy can be usedto ensure proper placement of the rasp within the disc space.

Once the end plates 20′, 22′ have been prepared with the rasp asindicated above, a box chisel 510 of the appropriate size is preferablyselected. Box chisel 510 is then inserted over the shaft 603 of the rasp600. Rotational alignment between the rasp 600 and the chisel 510 isprovided by the pin 703 of side handle 701 (see FIG. 13).

When rotational alignment between the rasp 600 and the box chisel 510achieved, the chisel 510 is slid along the shaft 603 of the rasp towardthe vertebrae 20, 22. The chisel 510 is then impacted (e.g., with slaphammer 501) against the vertebrae 20, 22 until edges 522 and 523 of thechisel 510 contact the back side 617 (shown in FIG. 15) of the rasp head(see FIG. 36). Thereafter, the rasp 600 and chisel 510 combination canbe removed from the intervertebral space using the slap hammer 501.

After the rasp 600 and box chisel 510 have been removed, an insertionhead 803 having a size corresponding to the size of the rasp 600 andchisel 510 is selected. The insertion sleeve 820 is placed over theshaft of the insertion tool 800 and slid toward the insertion head 803causing the arms 807, 808 of the insertion head 803 to be flexedtogether. Thereafter, the support member 341 of the implant 320 isinserted onto the insertion head 803 such that tabs 804, 805 of theinsertion head fit within the corresponding grooves 336, 337 of thesupport member 341 (see FIG. 37). The sleeve 820 is then slid away fromthe insertion head 803 and threaded on the handle 850 of the insertiontool 800. With the sleeve 820 pulled back, the arms 807, 808 of theinsertion head flex outwardly to securely hold the support member 341 onthe insertion head.

The insertion tool 800 is then used to insert the support member 341through the portal 52 into the intervertebral space between thevertebrae 20, 22. Light impaction may be utilized to deliver the supportmember 341 into its final position. Final positioning is achieved whenthe insertion head contacts a positive stop 27 formed in the vertebrae20, 22 by the chisel 510 (see FIG. 38). Thereafter, the inserter sleeve820 is unthreaded from the inserter handle 850 and pushed toward theinserter head 803 to release the inserter head 803 from the supportmember 341. The insertion tool 800 is then removed from the supportmember 341 leaving the support member 341 within the intervertebralspace.

After the support member 341 has been implanted, a growth member 321having a size that corresponds to the support member 341 is selected.Preferably, the growth member 321 has a height that is at least twomillimeters, and preferably about three millimeters larger than thecorresponding support member 341. A tool such as a forceps 29 is used toplace the growth member 321 into the channel (i.e., region 26 shown inFIGS. 10B-12) created by the chisel 510 (see FIG. 39). A tamp can beused to tap the growth member into the channel. Once the growth member321 is in its final position, the portal extractor 60 is used to removethe portal 52 as shown in FIG. 40. The procedure is then finalized byconducting conventional surgical closure and post-operative careprocedures.

V. Alternative Implant Configuration

FIGS. 41-44 illustrate an alternative embodiment of an implant 140.According to this embodiment, implant 140 includes a body 141 having a“C-shaped” configuration comprising a first arm 142 continuous with asecond arm 143 forming a space 144 therebetween. Body 141 also includesan external wall 146 and an internal wall 147. As best illustrated inFIGS. 8 a and 8 c, the facing surfaces of arms 142 and 143 are concave142 a, 143 a, respectively. First bearing surface 150 and second bearingsurface 151 are planar. However, in an alternative embodiment, one orboth of bearing surfaces 150 and 151 could be configured as describedfor implants 70, 80 or 100.

A central void 155 is bounded by inner wall 147 and is continuous withopening 144 between arms 142 and 143. Thus, body 141 is a supportcomponent which can receive a growth component 153 in central void 155.In the illustrated embodiment, growth component 153 can be a dowel ofcancellous bone.

The implants described herein can be included in a kit comprising aplurality of incrementally sized implants which can be selected for useby the clinician based on the size needed for a particular patient. Inother embodiments, kits will be provided which include instrumentationfor performing an implant procedure with or without a plurality ofincrementally sized implants. Further, surface preparation tools (e.g.,rasps and cutting tools) other than those specifically depicted hereincan be used to practice various aspects of the invention.

Having now described the present invention, it will be apparent to oneof ordinary skill in the art that many changes and modifications can bemade in the invention without departing from the spirit or scope of theappended claims.

1. A bone implant system comprising: a bone support member forintervertebral implantation, the bone support member having a partialring shape that defines a central cavity including a closed end and anopen end; and an elongate insertion tool for inserting the bone supportmember between adjacent vertebrae, the insertion tool including aninsertion head sized to fit securely within the central cavity of thebone support member such that the bone support member is retained on theinsertion tool during the insertion process; and an insert block forinsertion in the bone support member after implantation of the bonesupport member and removal of the insertion tool from the inner cavity,the insert block including a bone growth promoting material, the insertblock having a pre-manufactured size and shape adapted to substantiallyfill the inner cavity.
 2. The bone implant system of claim 1, whereinthe insertion head is sized and shaped to complement the shape of thecentral cavity.
 3. The bone implant system of claim 1, wherein theinsertion head is sized and shaped to occupy a majority of the centralcavity.
 4. The bone implant system of claim 1, wherein the bone supportmember and the insertion head include a rail and slot arrangement forsecuring the bone support member to the insert head.
 5. The implantsystem of claim 1, wherein the bone support member includes corticalbone and the insert block includes cancellous bone.
 6. The implantsystem of claim 5, wherein the insert block is a natural material. 7.The bone implant system of claim 4, wherein the rail and slotarrangement includes: opposing slots defined within the central cavityby the bone support member; oppositely positioned rails provided on theinsert head; the rails being configured to slide within the slots whenthe insert head is inserted into the central cavity.
 8. The bone implantsystem of claim 1, wherein the insertion head includes a curved distalnose and generally parallel sidewalls that extend proximally from thedistal nose.
 9. The bone implant system of claim 1, wherein the innercavity and the insert block have complementary shapes.
 10. The boneimplant system of claim 1, wherein the inner cavity is coextensive witha center of the bone support member.
 11. The bone implant system ofclaim 1, wherein the bone support member is non-threaded.
 12. A methodfor implanting a spinal implant between adjacent vertebrae, the spinalimplant including a bone support member and an insert block, the bonesupport member defining an inner cavity having an open end and a closedend, the method comprising: inserting the bone support member betweenthe adjacent vertebrae with an insertion tool having an end portionretained within the inner cavity; removing the end portion of theinsertion tool from the inner cavity of the bone support member afterimplantation of the bone support member; and inserting the insert blockinto the inner cavity after the end portion of the insertion tool hasbeen removed from the inner cavity.
 13. The method of claim 12 furthercomprising selecting an insert block with a shape that complements theshape of the inner cavity.
 14. The method of claim 12 further comprisingselecting an insert block with a shape that fills a majority of theinner cavity.
 15. The method of claim 12 wherein inserting the insertblock further comprising inserting an insert block that includescancellous bone.
 16. The method of claim 12 further comprising preparingthe adjacent vertebrae by rasping one or more of an endplate of theadjacent vertebrae.
 17. A bone implant system comprising: a bone supportmember for intervertebral implantation, the bone support member having apartial ring shape that defines a central cavity including a closed endand an open end; and an elongate insertion tool for inserting the bonesupport member between adjacent vertebrae, the insertion tool includingan insertion head sized to fit securely within the central cavity of thebone support member such that the bone support member is retained on theinsertion tool during the insertion process; and an insert block forinsertion in the bone support member after implantation of the bonesupport member and removal of the insertion tool from the inner cavity,the insert block including a bone growth promoting material, the insertblock having a pre-manufactured size and shape adapted to substantiallyfill the inner cavity, wherein the bone support member and the insertionhead include a rail and slot arrangement for securing the bone supportmember to the insert head.
 18. The system of claim 17, wherein theinsertion head is sized and shaped to complement the shape of thecentral cavity.
 19. The system of claim 17, wherein the bone supportmember and the insertion head include a rail and slot arrangement forsecuring the bone support member to the insert head.
 20. The system ofclaim 17, wherein the bone support member includes cortical bone and theinsert block includes cancellous bone.